Automatic clutch control means for press brakes



Jan. 20, 1953 H. H. GOLDBERG AUTOMATIC CLUTCH CONTROL MEANS FOR PRESSBRAKES Filed Dec. 10, 1951 ISnoentor Fig.5

HARRY H. GOLDBERG ,2 ENE:

Patented Jan. 20, 1953 AUTOMATIC CLUTCH CONTR OILMEAN S FOR' PRESS.BRAKES.

Harry I-I. .Gioldberg, .Denverrflolo.

Application December 10, 1951, @Serial N b.'260',81'6f:

l 2 Claims.

This invention relates to improvementsirr steel press brakes of thetypenow extensively employed', and relates more particularlyto an attachmentfor the automatic'control of the power transmitting clutch.

Press-brakes of the type to which this invention relates have astationary bed plate,- a ram plate positioned therea'bove, meanscomprising a cam shaft having camsoperatively connected with the ramplate,- means for turning the camshaft comprisin a "clutch, and pedal"means for'controlling the operation of i the clutch.

In the operation of presses of'this type; the clutch is closedbyexerting pressure on a pedal bar and opened whenthe pressure isremoved from'the'bar. As'long as-pressure'is applied'to the-bar; the camshaft continuesto turn and the operator'must thereforewatchthe'positionof the ram plate in order to open the clutch at theproper time: The operators attention must therefore be dividedbetweenthefeeding of the press and the control of the clutch to stop theram plat'e 'at the-proper place.

It is the object of this invention to provide such presses. withmeansthat locks the clutch in operative position when the pedal bar isdepressed-to close the clutch and which automatically releasesthelatchand-opens the clutch when the. ram plate "has" returned to apredetermined position atthe endsof-its-cycle.

A" further obj ect-"is' 'to' provide an attachment or-means thatwill-make it unnecessary for the operator to keep one foot in constantengagement with the pedal bar and limits such engagement to a singleapplication of force at the beginning of each cycle.

The above and other objects of this invention which may appear as thedescription proceeds are attained by means of a construction and anarrangement of parts which will now be described in detail, for whichpurpose reference will be had to the accompanying drawing in whichFigure 1 is a perspective view of a well known steel press brake showingthe same as it is now marketed, the attachment being indicated inposition thereon.

Figure 2 is a side elevation, looking towards the left in Fig. 1, andshows the attachment, which forms the subject of this application, inplace thereon;

Figure 3 is a view partly in section and partly in elevation, taken online 33 Fig. 2, showing the attachment to an enlarged scale;

Figure 4 is a side elevation looking towards the left in Fig. 3 and 21Figure" 5* is"a'view similarto that-shownin Fig: 3.

Referring now to the' drawing; reference nu:

I merals R" and IBL designate respectively" the right andthe left sidesof the housing; The sides are joined at their tops by a crown sectionII. The sidesareconnected near their lower-ends by bars l2 and l3 andbed plate I3a. Cam shaft I4 is" mounted for rotation in' bearings [5;two" of which have-been shown; Theshaft carries two eccentrics that aresurrounded by straps 16 which are adjustably connected with" ram plateI1. Powerisusually supplied'bya constantly operating electriomotor,which has not been shown; and motion is transmitted to the cam shaft bya clutch (notshown) which is opened and closed by a pedalmechanismcomprising the pivoted levers l8'and rod l8a and pedal rod [9.

The press brake shown in'Figs. 1 and 2 is on the market. and itsconstructionis well known. The above description has beengiven'merely'for the purpose .of facilitating the descriptionof theattachment and its operation; Referringnow to Figs. 1 and2, it will beseen that the free ends of L'levers l8.areiconnected by a pedal bar. orpedal rod. A spring, which is not visible in Fig. 1 serves to hold.leverlii' in the elevated clutchopen positionshown in. Fig. 2, and for.the purpose of visualelaritya spring S has been shown on the outsideand/this represents the hidden spring. When'the parts are in theposition shown in Fig. 2; the clutch is open and the ram plate isstationary. When levers I8 are moved to the position shown by dottedlines in Figs. 2 and 5, the clutch is closed, and shaft l4 turns movingthe ram plate in a vertical direction. It is customary to stop the shaftwith the eccentrics at top dead center and therefore when the cam shaftbegins to turn the ram plate starts moving downwardly. In the usual wayof operating the press, the operator must keep his foot on pedal rod [9until the cam shaft has made a complete turn, which becomes verytiresome.

The invention or attachment to which this application is directedconsists of a bracket 2| attached to the ram plate and, a latchingmechanism attached to side IUR near its lower end. The latching deviceconsists of a steel casting or forging that has a base 22, which issecured to the side by suitable means such as bolts 23. Extendingoutwardly from the base is an arm 24 that has two spaced lugs 25 betweenwhich is mounted for pivotation a bell crank shaped member having an arm26 which extends in a generally horizontal direction and a pawl 27 thatextends vertically. A rod 28 has its lower end pivoted at 29 to the endof arm 26 and extends upwardly through a hole in bracket 2| andterminates above the bracket in a threaded section to which twoadjusting nuts 30 are connected, one of which serves as a lock nut.Attached to rod 28, directly below bracket 2|, is an arm 3| that can bemoved longitudinally on rod 28 and be clamped in adjusted positions by aset screw 32 or any other suitable means. Attached to side IDR is ananchor loop 33 such as an eye bolt, which forms a stationary anchor forthe lower end of spring 34 whose upper end is attached to arm 3 1.Spring 34 is always under tension and therefore tends to move rod 28downwardly. From Fig. 5 it will be seen that the up and down movement ofrod 28 rocks pawl 21 about its pivot. When the ram plate is in itsuppermost position, as shown in Fig. 2, pawl 21 is in the full lineposition which is the position that corresponds to open position of theclutch. When the operator exerts sufficient pressure on pedal bar 19,levers I8 move to the dotted line position shown in Figs. 3 and 5 andcloses the clutch, whereupon the cam shaft starts turning and moves theram plate downwardly. As bracket 2| moves downwardly, spring 34 movesrod 28 downwardly and turns pawl 21 in a counterclockwise direction.When bracket 2| has moved away from nut 30, the pawl is then in thedotted line position shown in Fig. 5 and prevents levers l8 from movingupwardly in response to the force exerted by spring S; the clutchtherefore, remains closed until lever 18 is released which occurs whenbracket 2| in its upward movement engages nuts 30 and moves bar 28upwardly to a point where lever I8 is released whereupon spring Simmediately moves the parts to the full line position shown in Fig. 5and opens the clutch. The exact point at which lever I8 is released andthe clutch opens is determined by the position of nuts 30 and cantherefore be adjusted.

In the event that the automatic clutch release is not wanted, hook 35which is pivoted at 36 to the upper end of arm 31, is moved into thedotted line position shown in Fig. 5 and holds pawl 21 in inoperativeposition.

Attention is directed to the fact that presses equipped with theautomatic clutch latching and automatic clutch release do not requirethe operator to exert pressure on the pedal rod continuously during theentire cycle of ram plate movement as is now necessary. With pressesprovided with the control means above described, the operator exerts asingle pressure on the pedal rod, which moves it into latching position;he can then remove his foot from the pedal bar until he initiates thenext cycle.

This attachment is simple and can readily be attached to existingpresses. If the control means is built into the'machine at the factory,it is obvious that the several elements can be replaced by equivalentelements located differently, but still performing the same function.

What is claimed as new is:

1. The combination with a press brake having its working headcam-engaged with a shaft for reciprocation of a ram plate by rotation ofthe shaft, a clutch adapted to engage the shaft with driving means, aspring held foot treadle adapted to be depressed in the direction of theworking stroke of the ram plate, and clutch shifting means adapted toshift said clutch to the shaft engaging position responsive to thedepression of the foot treadle; of a bell crank with one arm forming ahook adapted to latch the foot treadle in its depressed position and theother arm forming a lever movable in the direction of the foot treadledepression to rotate the hook arm into latching position, means toresiliently hold the bell crank in the latching position, a rodconnected to the lever arm, a bracket on'the ram plate slidably engagingsaid rod, and a stop on the rod adapted to be engaged by the bracket atthe retracted position of the ram plate and to hold the bell crank inthe unlatching position at said retracted position.

2. A device in accordance with claim 1 in which means is provided forholding the bell crank in unlatching position independently of theposition of the ram plate.

HARRY H. GOLDBERG.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 945,551 Knoell Jan. 4, 19101,040,441 Seybold Oct. 8, 1912 1,102,609 Scherer July '7, 1914 2,052,752Criley Sept. 1, 1936 2,594,909 Georgefi Apr. 29, 1952

